1. Removal of Stubborn Organic Matter and Adhesives
Target Contaminants: Primarily addresses label adhesive (pressure-sensitive adhesive), grease, sugars, residual beverages, etc., that remain on the PET flakes after processes like crushing, friction washing, and cold washing.
Working Principle:Utilizes thermal energy (typically heating the washing medium to 70°C - 95°C) to reduce the viscosity of these organic pollutants, causing them to soften, dissolve, or emulsify, thereby making them easier to detach from the PET flake surfaces.

2. Loosening and Removal of Embedded Labels and Impurities
 In hot water, shrink sleeves (e.g., PE film) relax due to the heat, facilitating easier separation from the PET flakes.
Stubborn impurities embedded in cap threads or creases of the bottle body also become easier to wash out under the thermal effect.

3. Enhancement of Flake Whiteness and Luster
Hot washing effectively removes fine stains and oxidation layers adhering to the flake surfaces, significantly improving the visual whiteness and sense of purity of the recycled PET flakes. This is crucial for subsequent use in producing light-colored or transparent products.

4. Improvement of the Final Product's Intrinsic Viscosity (IV)
This is a key chemical function of hot washing. PET is prone to hydrolytic degradation at high temperatures, leading to a decrease in its Intrinsic Viscosity (IV value), which affects performance in spinning or bottle blowing.
The hot wash tank rapidly removes the surface layer of degraded, low-IV PET from the flakes, exposing the higher-quality, higher-IV PET within. This stabilizes and enhances the average IV value of the final rPET pellets.

5. Preparation for the Next Stage: "Friction Washing" or "Float-Sink Separation"
 After hot washing and chemical action, contaminants are loosened from the PET surface. Subsequent mechanical action through intensive friction washing, or the use of hot water float-sink separation (where density differences between materials are more pronounced in hot water), then thoroughly separates the dislodged impurities (such as PE/PP cap fragments).

6. Process Synergy (Often Combined with Chemicals)
 The hot wash tank typically has specialized cleaning agents (e.g., alkaline solutions) added. The synergistic effect of  Heat and Chemistry greatly improves cleaning efficiency, achieving better results in a shorter time.